The present invention relates to a novel catalyst basket for denitration and more particularly a catalyst basket which is used for denitration by a dry NH.sub.3 catalytic reduction method and which is disposed in an exhaust gas passage of a boiler or the like to remove nitrogen oxides (NO.sub.x) contained in exhaust gases.
The dry NH.sub.3 catalytic reduction method is well known in the art as a method for removing nitrogen oxides (NO.sub.x) contained in exhaust gases. According to this method, NH.sub.3 reduction catalysts for denitration are disposed in an exhaust gas passage.
With a denitration device accomplishing the dry NH.sub.3 catalytic reduction method in an exhaust gas discharge system for an automobile, it is well known in the art that a basket made of hard ceramics or steel and filled with catalysts is inserted into an exhaust gas passage of the exhaust gas discharge system. The single basket will suffice for this use since the exhaust gas passage is relatively small in inner diameter and the catalysts charged thereinto are accordingly smaller in size.
Meanwhile, an exhaust gas passage of an exhaust gas discharge system for a boiler or incinerator is in general three to ten meters in diameter and each catalyst element inserted into the passage is 100-150 mm in diameter and 700-1,500 mm in length. Such catalyst elements are arranged thousands to ten thousands in number to provide a denitration device.
With the denitration device carrying out the dry NH.sub.3 catalytic reduction method in the exhaust gas passage of a large-sized boiler or incinerator, relatively large catalyst elements are arranged thousands or ten thousands in number in the exhaust gas passage as described above so that catalyst element insertion operation itself is troublesome. Moreover, handling of the individual catalyst elements is difficult to carry out since the catalyst elements are sintered products and are easily susceptible to impact forces.
The catalyst elements are disposed on shelves in the exhaust gas passage. Direct disposition of the individual catalyst elements on the shelves will necessitate the shelves to have larger cross sections from the view point of mechanical strength, which may adversely affect passage of the exhaust gases and may accelerate accumulation of ash contained in the exhaust gases.
The present invention was made to overcome the above and other problems encountered in the conventional dry NH.sub.3 catalytic reduction type denitration device disposed in the exhaust gas passage of a large-sized boiler or incinerator and has for its object to provide a catalyst basket for denitration which makes it possible to handle a plurality of catalyst elements as a unit so that the protection and handling of the catalyst elements are ensured. Another object of the present invention is to provide a catalyst basket for denitration whereby a plurality of units of catalyst elements are disposed in the exhaust gas passage, thus providing a denitration device.
The above and other objects, effects, features and advantages of the present invention will become more apparant from the following description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.